Expect more heavy rains, Kenyans told


A woman with baby wades through a flooded path on her way to the hospital in Bombolulu, Mombasa County following heavy rains on November 16, 2023. 

Photo credit: Wachira Mwangi | Nation Media Group

What you need to know:

  • Meteorological Department urges Kenyans to play their part in minimising loss of lives and property damage.
  • Counties likely to experience landslides and mudslides are West Pokot, Elgeyo Marakwet, Kericho, Baringo, Nakuru and Murang’a.

El Nino season in Kenya and other parts of the world is slightly favoured to be “historically strong”, the US Climate Prediction Centre says. 

The season has a 54 per cent chance of being one of the strongest since 1950, data from the American agency shows. 

The odds are up from last month when the Climate Prediction Centre gave this year’s El Nino a 35 per cent chance of being among the strongest ever – like the ones witnessed in the 2015-2016 or 1997-1998 seasons. 

According to the 2023 data on oceanic-nino dipole (OND) rainfall driver projections by the Kenya Meteorological Department(KMD), downpours being experienced in most parts of the country will intensify into the new year.

The department adds that the current El Nino season is being driven by an oceanic nino index (ONI) of approximately 2.0, which very strong, almost as strong as the 1997 El-Nino season that was driven by an ONI of 2.4 – an El Nino regarded as the most destructive and deadly compared to the ones of 2006 and 2015.

“Nearly all models indicate El Nino will persist through the Northern Hemisphere winter 2023-24,” the Met said in its report.

“At its peak – November to January – a strong El Nino (ONI values at or greater than 1.5 degrees Celsius) is indicated by the dynamical model.”

KMD highlights in its official report on a climate pattern that describes the unusual warming of surface waters in the eastern Pacific Ocean while also explaining that models predict a strong El Nino season in Kenya.

It, however, adds that the values may not reach those of 1997.

“Basically, expect El Nino conditions during the October to December season. El Nino is a phenomenon that is characterised by warmer than average sea surface temperatures over the central and eastern equatorial Pacific region and cooler than average sea surface temperatures over the western equatorial Pacific Ocean,” Hannah Kimani, the assistant director sub-seasonal to seasonal forecasting at KMD told the Sunday Nation.

“El Nino usually leads to enhanced rainfall during the October-December short rains. Apart from El Nino, the above average rainfall being experienced is also driven by the Indian Ocean dipole (IOD).”

The rains are likely to lead to flooding in most parts of the country and landslides in the highland east and west of the Rift Valley.

Counties likely to experience landslides and mudslides are West Pokot, Elgeyo Marakwet, Kericho, Baringo, Nakuru and Murang’a.

“Kilungu in Makueni County could also experience some landslides,”she said. 

Ms Kimani said floods are likely to be experienced in low-lying areas in the north, northwest and northeast parts of Kenya.

Others told to brace themselves for floods are the southeastern lowlands and the Lake Victoria basin.

According to the forecaster, the Indian Ocean IOD is a natural climate cycle brought about by sustained changes in the difference between sea surface temperatures in the tropical western and eastern Indian Ocean, adjacent to the East African coast and south of Indonesia.

“This means as IOD and El Nino come together, there will be extraordinarily heavy rainfall,” Ms Kimani said. 

A positive IOD and El Nino is what is expected to fuel above average October to December rainfall.

“We have also observed that the ONI is at 1.1, compared to 1.6 in 1997,” she said. 

This is why models predict a strong El Nino but the values may not reach 2.4, which was recorded in 1997,.

An ONI of 2.4 is very strong but this year’s will reach 2.0 as per what the models are predicting.

“No El Nino behaves exactly like another,” Ms Kimani said, adding that ONI is a measure of the departure from normal sea surface temperature in the east-central Pacific Ocean and is the standard means by which every El Nino episode is determined, gauged, and forecast. 

“The moderate 2006 El Nino had an ONI of 0.6 while the strong one in 2015 had an ONI of 2.6. The two came with enhanced rainfall,” she said. 

“El Nino episodes are indicated by sea surface temperature increases of more than 0.5 degrees Celsius for at least five successive overlapping three-month seasons.” 

The KMD assistant director, however, added that the highest IOD index (>2.0) ever recorded by KMD, which saw enhanced rainfall throughout the country was in 2019, though it was not an El Nino year.

The 1997 IOD Index was above 2.0 but not as high as in 2019.

The Meteorological Department, however, told the Sunday Nation that it cannot tell if the 2.0 ONI it is predicting will obliterate the 2.4 recorded in 1997.

“All we can do is continue monitoring whatever is happening but chances are it may not go as high as in 1997. If it goes above 2.4, we will keep the country updated,” Ms Kimani said. 

The dry counties of Baringo, Garissa, Isiolo, Mandera, Marsabit, Samburu, Tana River, Turkana, Wajir should expect isolated cases of heavy rainfall, the department said. 

The same applies to the semi-arid counties of Embu, Kajiado, Kilifi, Kitui, Kwale, Laikipia, Lamu, Makueni, Meru, Narok, Nyeri, Taita Taveta, Tharaka Nithi and West Pokot.

“In 1997, Kenya did not have county Meteorological Service Directors. We were just giving national forecasts,” Ms Kimani told the Sunday Nation. 

“In 2023, we are issuing per county forecasts on weekly and monthly basis to ensure that Kenyans are safe. We must minimise the loss of lives and damage to property.”

Three weeks ago, Dr David Gikungu, the head of the Meteorological Department, also said the El Nino season rains would be enhanced. 

“Let us prepare for the enhanced rainfall as a result of the El Nino phenomena we find ourselves in,” Dr Gikungu said.